def abs(z):
    """
    Returns the magnitude of the given number
    
    Args:
        z (complex): The complex number to compute the polar angle of.

    Returns:
        the magnitude of the given number or the element-wise magnitudes of the given list.
    """
    if isinstance(z, (list, tuple)):
        return [abs(x) for x in z]
    elif isinstance(z, complex):
        return (z.real**2 + z.imag**2)**0.5
    elif isinstance(z, (float,int)):
        if z >= 0:
            return z
        else:
            return -z
    else:
       raise TypeError("Input type not supported.") 


# Test case 1: Input is a positive real number
x1 = 5
assert abs(x1) == 5
assert abs(x1 + 0j) == 5

# Test case 2: Input is a negative real number
x2 = -5
assert abs(x2) == 5
assert abs(x2 + 0j) == 5

# Test case 3: Input is a complex number with real and imaginary parts
z3 = 3 + 4j
assert abs(z3) == 5
assert abs(-z3) == 5
assert abs(0 + z3) == 5

# Test case 4: Input is a complex number with zero real part
z4 = 0 + 6j
assert abs(z4) == 6
assert abs(-z4) == 6
assert abs(0 + z4) == 6

# Test case 5: Input is a complex number with zero imaginary part
z5 = 8 + 0j
assert abs(z5) == 8
assert abs(-z5) == 8
assert abs(z5 + 0j) == 8

# Test case 6: Input is a complex number with both real and imaginary parts as zero
z6 = 0 + 0j
assert abs(z6) == 0
assert abs(-z6) == 0

# Test case 7: Input is a list of real numbers
lst1 = [1, -2, 3, -4, 5]
assert abs(lst1) == [1, 2, 3, 4, 5]
assert abs([x + 0j for x in lst1]) == [1, 2, 3, 4, 5]

# Test case 8: Input is a list of complex numbers
lst2 = [1 + 2j, -3 + 4j, 5 - 6j]
assert abs(lst2) == [2.23606797749979, 5.0, 7.810249675906654]
assert abs([-x for x in lst2]) == [2.23606797749979, 5.0, 7.810249675906654]
